题目：
The purpose of an air compressor unloading device is to （）
A.drain water from the air receiver
B.drain water from the cylinders
C.delay the compression process until the motor is up to speed
D.check pump alignment
答案：
参考答案：C
The purpose of an air compressor unloading device is to （）
A.drain water from the air receiver
B.drain water from the cylinders
C.delay the compression process until the motor is up to speed
D.check pump alignment
参考答案：C
